CHICAGO (CBS) – There may be a break in the case of murdered police officer Michael Flisk, 46, and former CHA cop Stephen Peters, 44. Chicago police confirm they have someone in custody. Sources say it is a 19-year-old man who lives near the crime scene.

CBS 2’s Dana Kozlov reports there was a huge police presence in the South Chicago neighborhood again Sunday. And even though police won’t say if they believe the person they have in custody is the killer, they are sure acting like he is.

Chicago police are not letting up. Dozens of gang unit officers swarmed the city’s South Chicago neighborhood, blanketing the area where police officer Michael Flisk and ex-CHA officer Stephen Peters were gunned down Friday.

They took advantage of the bright, sunny day to look for any evidence they might have missed, leaving the clear impression this case is a top priority.

That presence, and activists asking for the public’s help, are small comforts to Peters’ mother Laura.

“They’ll get him. They’ll get him,” she said.

Peters and Evidence Technician Flisk were in her garage Friday afternoon on the 8100 block of South Burnham Avenue, after a burglary there, when someone apparently walked up and shot them both in the head. The victims didn’t even have a chance to get their own guns.

Autopsies on Saturday determined both men died of multiple gunshot wounds, according to the Cook County Medical Examiner’s office. Both deaths were ruled homicides.

On Sunday afternoon, one block over, detectives towed the 19-year-old suspect’s car from in front of his home in the 8100 block of South Manistee Avenue. Those who know him say he’s a gang member with a record.

South Chicago resident Bobby Hill says the suspect has been locked up before.

He had previously been convicted of armed robbery and sentenced to six years in prison but was paroled on Sept. 14.

On Saturday, the Department of Corrections probation officers helped Chicago police by going into the neighborhood with a list of anyone on parole, questioning them and searching their homes, which is legal.

Flisk joined the Chicago Police Department in January of 1991. He was assigned to the Evidence Technician Team – South unit for the past three-and-a-half years.

He received 67 awards during the course of his 19-year career. He earned 55 Honorable Mentions among many other notable achievements highlighting courageous and distinguished service. He has a wife and four children and has three siblings in the Police Department.

A $20,000 reward is now being offered for information leading to an arrest and conviction in the Flisk case. The reward was initially $10,000, but increased Sunday after an anonymous donor offered $10,000 more through the Chicago Police Memorial Foundation, according to a release from CPD.

Anyone with information may place a confidential, toll-free call to (888) 976-7468 or call Area 2 Detectives at (312) 747-8272.

One high-ranking officer says 2010 has been the deadliest year for police officers in Chicago since the late 60’s or early 70’s.

CBS 2’s Dana Kozlov and the Sun-Times Media Wire contributed to this report.